Calcified coronary lesions present therapeutic challenges for the interventional cardiologist, and in many instances require high speed rotational atherectomy (RA) to allow for successful stent implantation. To date, those factors that predict the need for a priori rotational atherectomy have not been determined, and the decision is typically at the discretion of the operator.

A comparative post-hoc analysis of the randomized ROTAXUS and PREPARE-CALC studies was carried out, by virtue of the fact that both studies made provision for cross-over to rotational atherectomy (from balloon dilatation or modified balloon dilatation, respectively). Clinical, angiographic and procedural characteristics were compared between groups. Multivariate logistical regression techniques were employed to assess for the presence of patient- or lesion- specific factors which led to a necessity for RA. Based on the regression coefficients, a scoring system was developed, predictive of the need for RA in an individual patient.

A total of 220 patients were randomized to balloon predilatation in both trials, and of these 31 patients required bailout RA. There were no patient-specific characteristics which predicted a need for bailout RA. Lesion length (odds ratio [OR] 1.02, 95%CI 1.00-1.04, p=0.03), bifurcation lesion (OR 2.58, 95%CI 1.25-5.32, p=0.01), vessel tortuosity of > 45° (OR 3.79, 95%CI 1.85-7.76, p<0.001) and severe vessel calcification (OR 11.32, 95%CI 3.30-38.84, p<0.001) were predictive of the need for RA in multivariable analysis. In the scoring system, a value of 1 was assigned to the presence of a bifurcation lesion or tortuosity of an artery segment > 45 degrees, and a value of 2 to the presence of severe calcification, yielding a maximum score of 4. The greater the sum of the individual elements of the score, the more likely a lesion required an RA strategy. Internal validation analysis via c-statistics revealed good discrimination, with an AUC of 0.79 (95%CI 0.73-0.85). A cut-off of score of 3 correctly identified 79% of cases where RA was required, albeit at a cost of selecting 34% of cases where it was not necessary.

This study reveals, uniquely using data derived from randomized controlled trials, that attention to the above lesion characteristics can ensure the most expeditious use of time and resources, by allowing the operator to predict if a given coronary anatomy is likely to need an RA strategy. This allows for the optimization of procedure time, cost, radiation and contrast dose using a simple scoring system based on angiographic findings.